Control of airflow to an inflatable thermal device

ABSTRACT

A condition is detected between an inlet port of an inflatable thermal device, such as an inflatable thermal blanket, and an end of an air hose through which a flow of pressurized, thermally treated air is provided to the device by way of the inlet port. The condition may be disconnection of the end of the air hose from the inlet port or the identification of a particular style of inflatable thermal device. A response to the condition may include provision of a perceptible indication that the condition has occurred. Other responses may include cessation of the flow of air or changing an air flow characteristic.

[0001] This is a continuation in part of prior application Ser. No. 09/138,774, entitled DETECTION A CONDITION BETWEEN AN INFLATABLE THERMAL DEVICE AND AN AIR HOSE IN A CONVECTIVE WARMING SYSTEM, invented by Van Duren et al., and filed on Aug. 24, 1998.

BACKGROUND OF THE INVENTION

[0002] This invention relates to pressurized thermal systems that regulate human core temperature by convecting pressurized, thermally regulated air. More particularly, the invention relates to inflatable thermal blankets and the like that are used, for example, in a medical setting to deliver a bath of pressurized air which is heated, cooled, or ambient temperature, for the treatment of hypothermia or hyperthermia. In particular, pressurized, thermally regulated air is used to inflate such a device and is expelled therefrom onto a person or animal. Still more particularly, the invention relates to monitoring the operation of a pressurized thermal device in order to detect and respond to a potentially hazardous condition of its operation. Further, the invention relates to the identification of an inflatable thermal device and controlling the delivery air in response to the identification so that special services can be provided based on patient identity or inflatable device model number.

[0003] The International Electrotechnical Commission has promulgated a new standard (IEC 601-2-35) entitled Particular requirements for safety of blankets, pads and mattresses, intended for heating in medical use. This standard imposes requirements on the design and operation of convective warming systems. In particular, clause 46.101 states: “If omission of a part, or the interchange of parts of a multi-part heating device, will cause a safety hazard, the heating device shall be designed such that heat will be supplied only if all parts of the heating device are correctly positioned.” This requirement is intended to prevent human or equipment error leading to patient injury.

[0004] In convective warming systems, a pressurized thermal device is used to deliver a bath of pressurized, thermally-regulated air to a person, animal, or thing. The device is inflated with the pressurized, thermally-regulated air and has one or more surfaces adapted for expelling the air onto a person. Such devices may lie on a person, around a person, or under a person. U.S. Pat. Nos. 5,324,320 and 5,405,371, for example, describe inflatable thermal blankets that lie on a person, expelling pressurized, warmed air through a lower surface that faces the person. U.S. Pat. No. 5,300,101 describes another inflatable thermal device that lies around the sides and at least one end of a person. Other kinds of inflatable thermal devices are contemplated, including those lying under a person. Therefore, when used, the term “inflatable thermal device” is intended to invoke any and all blankets, pads, mattresses, covers, and equivalent structures that operate as just described.

[0005] Typically, the inflatable thermal devices of interest convect pressurized air in response to a pressurized flow of warmed, cooled, or ambient temperature air that is provided, for example, from a heater/blower unit through an air hose. Typically the inflatable device includes one or more inlet ports that receive one end of the air hose. The other end of the air hose is received in the heater/blower unit. When the heater/blower unit is turned on, air is warmed in the unit and pumped from the unit through the air hose to inflate the inflatable thermal device, whence the air is exhausted to warm or cool a person. Such devices may exhaust the air through a plurality of punched holes, through porous material, or through air permeable material.

[0006] One hazard in convective warming systems that use inflatable devices is the risk of overheating or burning a person. In the first instance, the air temperature may exceed a level necessary for proper treatment. In the second instance, the end of the air hose that is received in an inlet port may become dislodged and repositioned in such a way as to direct the pressurized, heated air flow directly onto a person. It is these hazards that are contemplated by the IEC standard. To date, means for detecting and mitigating these hazards have not been incorporated into the convective warming systems described above. Furthermore, in addition to the hazards contemplated by the new IEC standard, there is an operating deficiency common to many commercially available convective warming systems. This deficiency lies in the dependence of the air flow temperature at the distal end of an air hose on several environmental and design conditions which prevent accurate estimation of air hose outlet temperature.

[0007] The commercially available heater/blower units for convective warming systems include a heater and a blower which operate to provide a steady stream of temperature-conditioned air at a given mass flow. The temperature of the heated air ducted from the heater/blower unit through an air hose is tightly controlled at the heater/blower unit end of the air hose; however, the temperature of air flow introduced into the inflatable thermal device is a function of several factors, including, but not limited to: 1.) the thermal capacity of the unit; 2.) the blower capacity; 3.) the length, thermal conductivity, and thermal emissivity of the air hose between the unit and the device; 4.) the fluid flow resistance of the device; and, 5.) the ambient conditions, of which temperature and external air velocity are the most important.

[0008] The exhaust (output) temperature of the flow of air leaving a heater/blower unit is generally tightly controlled by a unit temperature controller. The temperature controller continually senses the output temperature at a port in the unit where the proximal (near) end of the air hose is received and adjusts the heater unit power to maintain the output temperature at constant setting. The temperature of the air flow at the distal (far) end of the air hose (that is, the inlet temperature to the inflatable thermal device), however, depends greatly on the conditions listed above.

[0009] None of the commercially-available convective warming systems have sensors in the inlet port to measure air flow temperature, which can result in uncertain and poorly controlled delivery of therapy. Some prior art devices, including devices made by the assignee of the instant application, have equipped the distal end of the air delivery hose (connected to the inlet port) with temperature sensors. However, these sensors can still be inaccurate, as they provide inaccurate readings if the hose is improperly connected to the inlet port.

[0010] With most of the presently available heater/blower systems, it is also possible to interconnect the blower units, hoses, and thermal blankets of different manufacturers. Because these components may not have been designed to work together, and because there are not always common standards, the patient can be inadvertently supplied with air at inappropriate flow rates and temperatures. Not only can the patient be harmed, it is also possible to damage the equipment. Further, some users may knowingly use equipment that is not designed to work together out of convenience. Clearly visible electrical contact points permit operators to bypass interlock safeguards. The concern for the improper use of equipment must be tempered with the ability to warm patients in emergency situations.

[0011] Accordingly there is a need to: 1.) prevent heater/blower unit misuse when the inflatable thermal device has been disconnected from the air hose; 2.) provide better control of air flow temperature at the distal end of the air hose irrespective of ambient conditions, resistive load of the inflatable thermal device, or heater/blower unit capability; and 3.) meet the requirements of the IEC standard.

SUMMARY OF THE INVENTION

[0012] The invention is based on the critical realization that the junction between the distal (far) end of an air hose and an inlet port of an inflatable thermal device provides a location where the continuity of the air flow path and the magnitudes of air flow characteristics such as temperature and pressure can be sensed or regulated. In this regard, a first circuit element may be provided that is integral with the pressurized thermal device at, in, or near an inlet port, while a second circuit element may be provided at, in, or on the distal end of the air hose. When the distal end of the air hose is received in the inlet port, the first and second circuit elements cooperate to provide a signal indicative of connection between the inlet port and the distal end. When the distal end of the air hose is not connected to the inflatable thermal device by way of the inlet port, the signal cannot be generated. Therefore, the presence or absence of the signal may be used to provide an indication of a connect/disconnect condition between the inlet port and the distal end of the air hose. Moreover, the information can be enriched by addition of one or more sensors at or near the junction between the inlet port and the distal end of the air hose to provide an indication of one or more air flow characteristics such as temperature or pressure, or both. It may be desirable to provide a power override function that turns off the heater/blower unit, modulates the temperature output of the unit, or places it in a standby condition in response either a disconnect condition indication or measurement of a temperature and/or pressure at the distal end of the air hose that deviates from a predetermined value.

[0013] In particular, the above-described invention is made more useful by making the insertion of the distal end of the air hose into the inlet port independent of any kind of rotational alignment, so that the operators does not need to take the time to align keys. The rotational independence of the connection permits the air hose to be rotated while in use without breaking the electrical connection between the first and second circuit elements. The inlet port first circuit element can be of a conductive annular ring, a hose card with a conductive ink surface, or a wireless communications radiator. The invention is also made more useful by using the first and second circuit elements to communicate the identity of a specific inflatable thermal device. In one aspect, electrical impedance is measured to determine an inflatable device type to determine air flow characteristics. In another aspect, the first circuit element is connected to an electronic identification tag to provide information such as device model number and patient identification.

[0014] In yet another aspect of the invention, flow of air to the inflatable thermal device is controlled mechanically, with the insertion of the distal end of the air hose into the inflatable thermal device. Several valve mechanisms can be used to block air flow from the air hose when the hose is not properly seated in the inlet port. When inserted, the valves are forced open to provide air to the inflatable thermal device.

[0015] Accordingly, it is an object to invent a convective warming system that includes a pressurized thermal device with the ability to sense and react to air flow conditions at a point where an air flow is provided through an inlet port of the device.

[0016] Another object is to disable, prevent, or attenuate the operation of a convective warming system when the inflatable thermal device becomes detached from a heater/blower unit.

[0017] Another object is to identify the inflatable thermal device, and to modify the flow of air, air temperature, or both, in response to the identification.

[0018] Another object is to determine the number of times the pressurized delivery device (blanket) is used or connected to the heater/blower unit.

[0019] These and other objects and advantages of this invention will become evident when the following detailed description is read in conjunction with the below-described drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020]FIG. 1. Is an illustration of a convective warming system in which the invention may be embodied;

[0021]FIG. 2 is a block diagram showing the elements of the invention and their relationships to each other and to the elements of a convective warming system;

[0022]FIG. 3A and 3B illustrate an air hose, an inflatable thermal device and elements of a presence sensor according to the invention that monitors continuity of the connection between the distal end of the air hose and an inlet port of the device;

[0023]FIGS. 4A and 4B illustrate the elements of FIGS. 3A and 3B, with the addition of an airflow sensor located at the inlet port;

[0024] FIGS. 5A-5D, illustrate the elements of FIGS. 3A and 3B with the addition of an airflow sensor located in the distal end;

[0025]FIGS. 6A and 6B illustrate an alternate embodiment of the presence sensor of FIGS. 3A and 3B;

[0026]FIG. 7 illustrates another alternate embodiment of the presence sensor of FIGS. 3A and 3B;

[0027]FIGS. 8A and 8B illustrate how the proximal end of the air hose may be coupled to a heater/blower unit according to the invention;

[0028]FIG. 9 shows a presence sensor in an inflatable thermal device in which an inlet port is provided as a sleeve; and

[0029]FIGS. 10A and 10B show an alternate embodiment of the presence detector of FIG. 9.

[0030]FIGS. 11A through 11C illustrate the inflatable thermal device where the inlet port includes a hose card.

[0031]FIGS. 12A through 12C illustrate an alternate aspect of the air hose of FIG. 11A or the air hose of FIGS. 6A, 6B, 7, 10A, and 10B.

[0032]FIGS. 13A and 13B illustrate a convective warming system using an electronic identification tag.

[0033]FIGS. 14A, 14B, 15A-15C, 16A, and 16B illustrate some example of mechanical solutions to the problem of controlling air flow to an inflatable thermal device.

[0034]FIG. 17 illustrates a method for indicating a condition in a system including an inflatable thermal device, corresponding to FIGS. 11A-11C, and FIGS. 12A-12C.

[0035]FIG. 18 is a flowchart illustrating a method for indicating a condition in a system including an inflatable thermal device, corresponding to FIGS. 13A and 13B.

[0036]FIG. 19 is a flowchart illustrating a method for controlling air flow in a system including an inflatable thermal device, corresponding to FIGS. 14A-14B, 15A-15C, and 16A-16B.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037]FIG. 1 illustrates a convective warming system that is operated to control the body temperature of a person by convecting thermally-regulated air from an inflatable thermal device in the direction of the person's skin. The convective warming system of FIG. 1 provides a stream of pressurized, thermally-regulated air to an inflatable thermal device through an inlet port of the device. In FIG. 1, the inflatable thermal device is an inflatable thermal blanket, of the type sold by Augustine Medical, Inc. under the BAIR HUGGER7 trademark. This, however, is for purposes of illustration only. In fact, any and all equivalent inflatable thermal devices including blankets, pads, mattresses, covers, and equivalent structures are intended to enjoy the benefits of this invention.

[0038] With greater specificity, the convective warming system of FIG. 1 includes an inflatable thermal device 10 having one or more inlet ports through which a flow of pressurized, thermally-regulated air is admitted to inflate the inflatable thermal device 10. One such inlet port is indicated by reference numeral 11. In the BAIR HUGGER7 family of inflatable thermal blankets, inlet ports typically comprise an opening into an inflatable structure and a stiff planar member of cardboard having an aperture. The planar member of cardboard is mounted to the inflatable structure such that the aperture in the member is aligned with the opening in the inflatable structure. The planar member is commonly referred to as a “hose card” because it provides a flat, card-like structural element that receives and supports the distal end of an air hose when the distal end is joined, mated, coupled or received in the inlet port. However, this invention is not intended to be limited to an inflatable thermal device with such inlet ports. In fact, in the inflatable thermal blanket art many inlet port structures are known and include, for example, sleeves, openings, collars, and the like. Furthermore, an inflatable thermal device may include more than one inlet port. In this regard, many models of inflatable thermal devices have two—and sometimes more—inlet ports located at various positions in order to provide flexibility in arranging the elements of a convective warming system.

[0039] In the convective warming system of FIG. 1, the inflatable thermal device 10 is inflated by a stream of pressurized, thermally-regulated (warmed or cooled) air provided through an air hose 12 having a distal (far) end 14 and proximal (near) end 15. The distal end 14 is joined, mated, coupled, or received in one of the inlet ports of the inflatable thermal device 10. In FIG. 1, the distal end 14 is received in the inlet port 11. In other words, the inlet port 11 and the distal end 14 form a junction through which an air flow is provided to inflate the inflatable thermal device 10. A heater/blower unit 18 generates and provides a flow of pressurized, thermally-regulated air (hereinafter referred to as “an airflow”). In this regard, the unit 18 includes a port 19 in which the proximal end 15 of the air hose 12 is received. Through the port 19, the proximal end 15 is coupled, mated, received in, or otherwise joined to an outlet of a blower 20. The unit 18 includes a control unit 21 with user-accessible controls that may be used to set levels or magnitudes of air flow heat and air flow velocity. A signal for air flow velocity is provided by the control unit 21 on signal path 22 where it is coupled to the blower 20 to control the speed of a blower motor (not shown) that propels air through the blower 20. The control unit 21 further generates a signal on signal path 23 that controls the operation of a heater 24 disposed near the outlet of the blower 20 for heating the air flow. Heater/blower units with user-accessible controls as just described are commercially available. Examples are the 200, 500, and 700 series warming units available from Augustine Medical, Inc.

[0040] In the example selected for illustration of the convective warming system of FIG. 1, the inflatable thermal device 10 is placed on a person 26. This is not intended to limit the application of this invention to warming only or to use with humans. Indeed, it may be used in any system that thermally regulates persons, animals, or things using an inflatable thermal device.

[0041] Refer now to FIG. 2 for an understanding of the invention. Although FIG. 2 includes a set of specifically-described elements, it is to be understood that wherever any such elements have structural and/or functional equivalents, such alternatives are considered to be within the scope of the invention. In FIG. 2, a convective warming system constructed and operated according to the invention includes an inflatable thermal device (not shown) having one or more inlet ports, one of which is indicated by reference numeral 11. The distal end 14 of the air hose 12 is intended to be coupled to or received in the inlet port 11; however, these elements are shown separated in FIG. 2 in order to more clearly illustrate the complement of elements that make up the invention. The proximal end 15 of the air hose 12 is received in the port 19 of the heater/blower unit 18. The invention contemplates the combination of the just-described elements with a combination of elements that operate cooperatively to detect a condition between the distal end 14 of the air hose 12 and the inlet port 11 of the inflatable thermal device. These elements include a first circuit element 40 that is disposed in, on, at or near the inlet port 11. For example, the first circuit element 40 may be formed an as integral part of a hose card 30. A second circuit element 42 is located in, on, at, or near the distal end 14 of the air hose 12, and a signal path including one or more signal conductors 43 extends in or along the air hose 12 to the proximal end 15. At or near the proximal end 15 of the air hose 12, the signal path 43 is connected at connector 44 to the control unit 21 of the heater/blower unit 18. The combination of elements 40, 42 and 43 provides a circuit for detecting a condition that may develop or exist between the distal end 14 of the air hose 12 and the inlet port 11. In other words, these elements enable the generation, conduction, or detection of a signal that represents the condition. Such a condition may be embodied, for example, in the disengagement of the distal end 14 from the inlet port 11 while the heater/blower unit 18 is operating. Another condition, for example, could include a change in the temperature of the air flow through the distal end 14 or the inlet port 11, or through the junction formed between the distal end 14 and the inlet port 11 while the heater/blower unit 18 is operating. Yet another condition may be a change in the air flow velocity through the distal end 14 or the inlet port, or through the junction formed between the distal end 14 and the inlet port 11 while the unit 18 is operating. In this latter regard, the inverse of the condition would correspond to a decrease in the air flow resistance or a decrease in the air pressure at the distal end 14 of the air hose 12 or the inlet port 11, or in the junction between the distal end 14 and the inlet port 11 while the unit 18 is operating. Whatever the condition or conditions that the invention is deployed to detect, sensing is provided by cooperative operation between the first circuit element 40 and the second circuit element 42 when the distal end 14 is joined, mated, coupled or received in the inlet port 11. In this regard, the junction formed between the distal end 14 and the inlet port 11 brings the first and second circuit elements 40 and 42 into close proximity and/or alignment. For so long as the proximity and/or alignment is maintained while the heater/blower unit 18 is operating, a first indication or signal may be generated and conducted on the signal path 43 to the control unit 21. A change in the condition is sensed by the cooperative operation of the first and second circuit elements 40 and 42, with the change in condition causing a change in the signal conducted on 43. A change in the signal conducted on 43 that is observed by the control unit 21 while the heater/blower unit 18 is operating causes the control unit 21 to take any one or more of a number of actions. First, the control unit 21 may simply cause the generation of a perceptible indication. In this regard, an indicator 46 may provide a visual and/or audible indication of a changed condition. In addition, or alternatively, the control unit 21 may respond to a change in condition by changing the motor speed of the blower 20 and/or the temperature of the warning element 24. Further, the control unit 21 may be designed or adapted to shut down or stop the operation of the heater/blower unit 18 altogether, or to place it in a standby state during which the temperature and/or velocity of the flow of air may be reduced.

[0042] The cooperative operation of the first and second circuit elements can also provide a “first necessary condition” for starting the heater/blower unit 18, preventing it from being turned on, or becoming fully operational after being turned on, in response to disconnection or non-connection of the distal end 14 and the inlet port 11 prior to operation of the heater/blower unit 18. Stated another way, the invention would permit the heater/blower unit 18 to be turned on, or to be fully operational only upon detection of joinder, coupling, or mating of the distal end 14 with the inlet port 11.

[0043]FIGS. 3A and 3B illustrate an embodiment of the invention wherein mating of the air hose distal end with the inlet port is detected and indicated. Although these figures illustrate an inlet port of a certain construction, those skilled in the art will realize that the principles represented in these figures can be applied to other air hose/inlet port configurations. In FIGS. 3A and 3B, the hose card 30 is shown mounted on the inflatable thermal device 10 at the inlet port 11. The distal end 14 of the air hose has mounted to it a mechanism that aligns the distal end 14 with the inlet port 11 thereby to join, couple, or mate these elements, or otherwise form a junction between them. The mechanism includes a planar member 50 having generally the same shape and construction as the hose card 30 with the addition of an extending edge 52 that transitions into a lip 53. The extending edge 52 extends substantially along three sides of the periphery of the planar member 50 so that the distal end 14 can be joined, mated, coupled or received in the inlet port 11 by engaging the edges 31 of the hose card 30 between the lip 53 and a surface of the planar member 50. In FIGS. 3A and 3B, a first circuit element 55 is incorporated into the structure of the hose card 30 laterally of the opening in the hose card 30 that communicates with the inlet port 11. A second circuit element 57 is disposed in the planar member 50 laterally of the opening in the distal end 14 of the air hose 12. One or more signal conductors 58 are disposed in (or on) the air hose 12, extending from the distal end 14, along the air hose 12 toward its proximal end (not shown in these figures). Integration of signal wires into an air hose is within the ambit of modern manufacturing technology. Reference is given, for example, to vacuum cleaner hoses with embedded power conductors. In the figures, two electrical wires 58 a and 58 b are shown: their purpose is to conduct signals to the control unit 21. When the hose card 30 is received between the lip 53 and the planar member 50 so that the opening in the distal end 14 is aligned with the inlet port 11, the first circuit element 55 and the second circuit element 57 cooperate to complete or close a circuit between the one or more conductors 58 a and 58 b that is connected to the control unit 21. Many possible configurations of this circuit are possible for implementing as much of the invention as is illustrated in FIGS. 3A and 3B. For example, the first circuit element 55 may comprise a magnetic member and the second circuit element 57 may comprise a reed switch or a Hall effect device. In this case, when the first and second circuit elements 55 and 57 are placed in close proximity by mating of the distal end 14 with the inlet port 11, the magnetic member 55 causes the reed switch to close, connecting the two electrical conductors 58 a and 58 b, thereby creating a signal pathway along which a signal may be conducted. Conversely, when the distal end 14 is disengaged from the inlet port 11, the first and second circuit members 55 and 57 will be moved apart, causing the reed switch to open, which will disable, interrupt or open the signal path just described. This of course will prevent the conduction of a signal. Other mechanisms may be used for the first and second circuit elements 55 and 57 and for the one or more conductors 58 a and 58 b. For example, the first circuit element 55 may comprise a spring-loaded bar of conductive material, while the second circuit element 57 may comprise two spaced-apart terminals or posts to which the electrical conductors 58 a and 58 b are respectively connected. When the first and second circuit elements 55 and 57 are in close proximity, it is contemplated that the conductive bar in the hose card 30 would span and contact the posts, providing a conductive path therebetween. In yet another alternate implementation, the first circuit element 55 may comprise a spring-loaded, protruding member and the second circuit element 57 could comprise a mechanical switch that is operated by the protruding member when the distal end 14 is joined to the inlet port 11. In yet another implementation, the circuit could be an optical one in which the conductors 58 a and 58 b are optical fibers that terminate in optical connectors in the second circuit element 57. In this case, the first circuit element 55 could include an optical coupler that would complete an optical signal path between the ends of the two optical conductors. Alternatively, means exist for implementing an optical circuit using a single optical fiber terminated at the second circuit element 57 and a mirror incorporated in the first circuit element 55.

[0044] The first and second circuit elements 55 and 57 in FIGS. 3A and 3B operate cooperatively to provide a sensor-like function. In this regard, the sensor could be termed a “presence” sensor in that it senses the presence of the inlet port 11 from the standpoint of the distal end 14, or, conversely, it senses the presence of the distal end 14 with respect to the inlet port 11. From another point of view, the first and second circuit elements operate cooperatively as a switch with OPEN and CLOSED positions. The OPEN position would indicate separation or disconnection between the distal end 14 and the inlet port 11 or discontinuity of the junction formed between the distal end 14 and the inlet port 11. The CLOSED position, on the other hand, would indicate joining or connection of the distal end 14 with the inlet port 11, or continuity of the junction formed therebetween.

[0045]FIGS. 4A and 4B illustrate how the information provided by the simple two-state switch of FIGS. 3A and 3B can be enriched by provision of an air flow sensor at the junction formed between the distal end 14 and inlet port 11. In the description an Aair flow sensor≅ is a sensor that detects one or more air flow conditions and causes generation of a signal having a component that reports the magnitude of the sensed conditions(s). The air flow conditions may include, for example, temperature and velocity. In FIGS. 4A and 4B, the first circuit element comprehends a first conductive contact element 55 a, a second conductive contact element 55 b and a sensor 55 c. The first and second elements 55 a and 55 b are physically and electrically connected to the sensor 55 c, which is disposed in the opening of the hose card 30 in alignment with the inlet port 11. Again, the elements 55 a, 55 b, and 55 c are integrated into the structure of the hose card 30, although this is not intended to limit the implementation of a sensor at the junction between the distal end 14 and the inlet port 11. The second circuit element includes first and second conductive contact elements 57 a and 57 b disposed in the planar member 50 laterally of the opening in the distal end 14. When the planar member 50 fully engages the hose card 30 to join the distal end 14 with the inlet port 11, the contact element 55 a mechanically and electrically contacts the contact element 57 a, while the contact element 55 b, physically and electrically contacts the contact element 57 b. The electrical conductors 58 a and 58 b are connected, respectively, to the second circuit element contact elements 57 a and 57 b. Now, when the hose card 30 is engaged by the planar member 50, the presence sensor function will be performed by completion of an electrical signal path comprising 58 a, 57 a, 55 a, 55 c, 55 b, 57 b, and 58 b. In addition, the sensor 55 c, being disposed in the junction formed between the distal end 14 and the inlet port 11 provides the ability to sense and indicate characteristics of the air flow in the junction. In this regard, assuming that the sensor 55 c comprises a thermocouple, the temperature of the air flow could be measured and reported in the form of a signal. The sensor 55 c could also be configured to sense the velocity of the air flow at the same point using a hot-wire anemometer, for example. Moreover, two sensors and two circuits could be incorporated in the manner illustrated in FIGS. 4A and 4B to indicate presence, air flow temperature, and air flow velocity, or any combination thereof. Manifestly, optical elements exist which may be assembled using FIGS. 4A and 4B and the description just given to implement presence, temperature, and/or pressure sensing at the junction between the distal end 14 and inlet port 11.

[0046]FIGS. 5A and 5B illustrate disposition of a sensor in, at, on, or near the distal end 14. In this case, the first circuit element 55 may comprise a magnetic piece, a spring-loaded activator for a mechanical switch, or spring-loaded conductive strip. At the distal end 14, the second circuit element includes a terminal element 57 a and a sensor element 57 c. The terminal element 57 a operates cooperatively with the first circuit element 55 to complete an electrical circuit allowing the sensor 57 c to operate in the junction between the distal end 14 and inlet port 11. In this case, the contact element 57 a may comprise a reed switch, a Hall effect device, a mechanical switch, or two conductive posts, while the sensor element 57 c may comprise a thermocouple or an air velocity sensor. As with the example illustrated in FIGS. 4A and 4B, the examples of FIGS. 5A and 5B may incorporate more than one sensor at or near the distal end 14 and may sense presence, temperature and/or velocity. Furthermore, optical elements exist that could be incorporated to provide an analog of the electrical circuit shown in FIGS. 5A and 5B.

[0047]FIGS. 5C and 5D continue the illustration of the invention presented in FIGS. 5A and 5B. FIG. 5C shows the planar member 50 engaged with the hose cord 30 thereby to join, couple, or mate the distal end 14 with the inlet port 11. FIG. 5D is a side sectional elevation view taken along lines D-D in FIG. 5C. In FIG. 5D, the air hose 12, has a conventional construction that includes a flexible side wall 12 s. In addition, the conductors 58 a and 58 b are embedded in, formed in, or attached to the side wall 12 s. The air hose 12 terminates at the distal end 14 in a cup-shaped plastic member 14 a having a disk-shaped opening 14 o. The rim of the plastic member 14 a is attached to the planar member 50. The planar member 50 includes a first plate 50 p, preferably a plastic piece to which the rim of the plastic member 14 a is bonded or joined. Another plastic piece 50 pp is attached to the plastic piece 50 p; this piece 50 pp includes the extending side wall 52 and the lip 53. The pieces 50 p and 50 pp are joined or otherwise bonded together to form the planar member 50 as a single, unitary piece. The thermocouple 57 c is held between the two pieces 50 p and 50 pp and includes a portion that extends across an opening 50 o provided through the planar member 50. The hose card 30 includes two planar pieces 30 p and 30 pp that are glued or bonded together. An opening 30 o in communication with the inlet port 11 aligns with the openings 50 o and 14 o so that an air flow path extends through the air hose 12 and the openings 14 o, 50 o and 30 o. One contact 57 a is fixed in the planar member 50 at a location where it is contacted by the shorting bar 55 when the planar member 50 is seated on the hose card 30 as shown in FIGS. 5C and 5D.

[0048]FIGS. 6A and 6B illustrate an alternative embodiment of a presence sensor in which the opening in the center of the hose card 30 includes an edge 30 e on and adjacent to which a conductive material 55 m is disposed. The distal end 14 of the air hose 12 is configured as a nozzle 14 n having a circumferential groove 14 g in which two strips of conductive material 57 s are disposed. Each of the strips 57 s is connected to a respective one of the conductors 58 a and 58 b so that when the nozzle 14 n is inserted into the hole in the hose card 30, the groove 14 g seats on the edge 30 e and the material 55 m completes or closes an electrically conductive pathway between the strips 57 s.

[0049] Yet another implementation of the presence sensor is illustrated in FIG. 7 wherein the distal end 14 of the air hose 12 includes the nozzle 14 n which transitions to a collar 14 c within which a coil 57 i is embedded. The coil 57 i is connected to and driven by the conductors 58 a and 58 b. Disconnected from the hose card 30, the coil 57 i exhibits an impedance having an electromagnetic characteristic (impedance, with an inductive component). A second coil 55 i is embedded in the hose card 30 e around the edge 30 e. Now, when the distal end 14 of the air hose 12 is seated in the hose card so that the collar 14 c is adjacent the edge 30 e, the impedance driven by the conductors 58 a and 58 b has a value measurably different from that exhibited by the coil 57 i when the distal end 14 is not seated in the hose card 30. Alternatively, the coils 57 i and 55 i could be replaced with insulated conductive elements that exhibit a measurable capacitance whose value changes when the distal end 14 and the inlet port 11 are connected and disconnected.

[0050] One way in which to measure a change in an electromagnetic characteristic at the junction between the distal end 14 and the inlet port 11 would be to drive the circuit 58 a, 57 i, 58 b with a signal of known frequency generated by the control unit 21. A change in the characteristic would be manifested by a change in frequency of the signal.

[0051] Another way in which to measure a change in an electromagnetic characteristic at the junction between the distal end 14 and the inlet port 11 would be to drive the circuit 58 a, 57 i, 58 b with a variable frequency signal that includes a known frequency generated by the control unit 21. A change in the characteristic would be manifested by a change in the impedance of the circuit at the known frequency of the signal.

[0052] Yet another implementation of the presence sensor is to imbed a small piece of magnetic material in the hose card. This material may be excited with a single pulse from circuit 58 a, 57I, 58 b. The activation of the magnetic material would then cause resonance in that material with a back scattering of a characteristic frequency. This frequency would then be sensed through the same activating circuit of 58 a, 57I, 58 b.

[0053]FIGS. 8A and 8B illustrate how a connection is made to the heater/blower unit 18 at the proximal end of 15 of the air hose 12, to provide continuity of a signal pathway to the control unit 21 (not shown). In this regard, a connector plug 44 p is mounted on a proximal end nozzle 15 n. The conductors 58 a and 58 b terminate on respective pins of the plug 44 p. When the nozzle 15 n is received in the port 19 of the unit 18, the pins of the plug 44 p are received in respective receptacles of a connector socket 44 s mounted on the unit 18, adjacent to the port 19, in alignment with the pins of the plug 14 p. As shown in FIG. 8B, when the plug 44 p and socket 44 s are mated, the indicator 46 provides (in this example) a visual indication of joinder, mating, coupling, or connection between the distal end 14 of the air hose 12 and one of one or more inlet ports of an inflatable thermal device.

[0054]FIGS. 9, 10A and 10B illustrate how the invention may be adapted to inlet ports having sleeve-like constructions. Referring to FIG. 9, the distal end 14 of the air hose 12 has the nozzle 14 n in which a slot 14 s is cut. An edge 14 e of the slot is exposed and elements of conductive material 57 m are placed on the edge 14 e, in opposition across the slot 14 s. The inlet port 11 is embodied in a sleeve 70 of material that extends from and opens into an inflatable thermal device (not shown). An alignment and contact mechanism 72 is mounted on the inside of the sleeve 70 by appropriate means including, for example, gluing between the inside surface of the sleeve and the upper surface 72 u of the alignment mechanism 72. The alignment mechanism 72 may be a molded plastic piece that generally has the shape of the slot 14 s and includes a peripheral slot-like recess 72 s that receives the edge 14 e of the slot 14 s. A strip of conductive material 55 m is disposed in the alignment mechanism 72, protruding in the opposed places into the peripheral slot-like recess 72 s. When the slot 14 s is seated on the alignment mechanism 72, an electrical circuit is completed or closed between the conductive material elements 57 m by way of the strip of conductive material 55 m. In FIGS. 10A and 10B, the end of the sleeve 70 has an elastic material integrated into the material of the sleeve 70 to form an elastic portion 70 e. On the inside surface of the elastic portion 70 e a ring of conductive material 55 m is attached. The distal end 14 of the air hose 12 has substantially the same construction as that illustrated in FIGS. 6A and 6B, with the exception that the circumferential groove 14 g is omitted. To join, couple, the distal end 14 in the inlet port 11 via the sleeve 70, the elastic region 70 e is expanded, and the distal end 14 is slid into the sleeve 70 until the collar 14 c is in the portion of the elastic region 70 e that is girded on its inside surface by the ring of conductive material 55 m, which closes or otherwise completes an electrical pathway between the conductive elements 57 s. The nozzle 14 n is retained in the sleeve 70 by the grip of the elastic region 70 e on the nozzle's outside surface.

[0055]FIGS. 11A through 11C illustrate the inflatable thermal device where the inlet port 100 includes a hose card 102. It should be understood that the inlet port 100 and hose card 102 are typically a component of an inflatable thermal device which is not shown as an effort to simplify the drawings. The hose card 102 is used to provide the first circuit element electrical connection and to provide mechanical stability to the air hose/inlet port interface. As shown in FIGS. 6A, 6B, 7, 10A, and 10B, the first circuit element 104 is annular, surrounding the inlet port 100. This permits the first, or distal end 106 of air hose 108 to freely rotate in the inlet port 100 without a loss of electrical continuity. The first hose end also includes the second circuit element, two electrical contacts 110 a and 110 b are shown, but in some aspects of the invention the second circuit element is a single electrical contact. The second circuit element 110 a/110 b cooperates with the first circuit element to enable a signal representing a connection between the first end 106 of the air hose 108 and the inlet port 100. As mentioned above, the connection is made independent of the rotational alignment of the air hose in the inlet port. The rotational alignment is represented by reference designator 112. In a simple aspect of the invention, the first 104 and second 110 a/110 b circuit elements are electrical contacts, the joining of which completes an electrical circuit, signifying that the air hose 108 is properly mated in the inlet port 100. As is explained in more detail below, that connection of first 104 and second 110 a/110 b circuit elements can be used to conduct signals with information content which permit a more complex determination of the condition of the air hose 108 in the inlet port 100.

[0056] In one aspect of the invention, as shown, the first circuit is made up of a plurality of members, such as member 114, which have a saw-tooth shape ending in a peak pointing toward the center of the inlet port 100. Typically, the hose card is made of cardboard, or some similarly pliable material so that as the air hose first end 106 is inserted in the inlet port 100, the members 114 are deformed. Due to the tooth shape of the members 114, which increases in thickness in moving towards the base of the tooth, the members gradually stiffen as the first hose end 106 is inserted.

[0057]FIG. 11B illustrates the hose card 102 of FIG. 11A with a mated hose 108. It is well known for the diameter of a hose to gradually increase in travel from the end for the purpose of making a snug connection with a mating port. One advantage of such a connection is the elimination of intermittent connection events which would be a nuisance for operators. Another advantage is in ensuring a reliable electrical connection, or a consistent value of resistance generated between deforming members 114 and second circuit elements 110 a and 110 b.

[0058]FIG. 11C is a cross-sectional view of the air hose 108 of FIG. 11B illustrating a modification to better receive the deformable members 114. An annular groove 116 is formed in the first hose end around the outside diameter. The second circuit element 110 a is seated the groove 116. As the air hose 108 is inserted into the inlet port 110, the members 114 are bent. The mechanical, and therefore electrical, connection between the first circuit element 104 and the second circuit element 110 a is captured by the action of the stiffened members 114, as well as by the bent shape of the members 114.

[0059] To complete the electrical connection required for the first 104 and second 110 a/110 b circuit elements to cooperate, the first circuit element deformable members 114 have a surface coated with a conductive ink. The ink can include conductive elements such as copper, silver, and carbon, but the invention is not limited to the use of just the named connective elements. One conductive ink found to be effective is manufactured by Acheson, under the part number of SS 24600. The conductive ink can be formulated to have a known resistance, permitting the controller to differentiate between different types of thermal devices. For example, it may be desirable to have the controller operate the blower under a first set of temperature and airflow parameters when a first kind of inflatable thermal device, having a first resistance measurement, is connected to the air hose. The control circuit is able to measure and recognize different resistance values, correlate these resistance measurements to corresponding inflatable thermal devices, and modify the temperature and airflow parameters in response to the measured resistance, so that a variety of inflatable thermal device can be operated at predetermined parameters from a single blower unit.

[0060]FIGS. 12A through 12C illustrate an alternate aspect of the air hose 108 of FIG. 11A or the air hose 12 of FIGS. 6A, 6B, 7, 10A, and 10B. That is, the second circuit element to be described can be used with a variety of first circuit element designs, including the hose card first circuit element. The air hose first end 106 is manufactured from a partially resistive material, such as a conductive polymer, in which electrical conductivity can be varied by loading the material with conductants such as carbon. These materials have a surface conductivity in-between standard plastics and metal. Conductive polymers are lighter than metal, and less subject to denting. The PermaStat® family of products manufactured by the RTP company is an example of such a material. The second circuit element is formed from a highly conductive element, such as metallic wire which is embedded in the polymer material. Two conductive elements 120 a and 120 b are shown. Electrical current can pass from the polymer nozzle surface to the embedded wires 120 a/120 b, with the electrical resistance being at a minimum at the surface area immediately overlying the wires. That is, the second circuit element includes the conductive elements 120 a/120 b and the polymer surface overlying the elements. Further, the first circuit element 104 and second circuit element 110 a/110 b cooperate to enable a signal between the first circuit element (however defined) and the polymer hose surface immediately overlying the highly conductive element 120 a/120 b. In other aspects of the invention, the polymer surface overlying the conductive elements 120 a/120 b is formed in a separate fabrication process from the deposition of the conductive elements and/or the formation of supporting layer of nozzle material that need not be the highly resistive polymer.

[0061] Regardless of whether the first circuit element is a simple electrical contact, a contact as described in the explanation of FIGS. 6A, 6B, 7, 10A, and 10B, or the hose card design described in the explanation of FIGS. 11A-11C, the impedance, resistivity, or conductance across the element can be measured and defined as a first impedance. Likewise, regardless of whether the second circuit element is as described in FIGS. 6A, 6B, 7, 10A, 10B, 11A-C, or 12A-C, the impedance can be measured and defined as the second impedance. Then, the cooperation of the first 104 and second 110 a/110 b circuit elements provides an impedance which represents a connection between the first end of the hose and the inlet port. That is, the combination of impedances represents a condition where the air hose 108 is properly connected to the inlet port 100. Too small an impedance could represent an improper connection or a short. Too large an impedance typically represents a disconnection in the cable connecting the sensor to the controller circuitry, such as the air hose 108 being improperly mated to inlet port 100. In some aspects, the first impedance may be significantly larger than the second impedance, so that in measuring the series line impedance of a properly mated air hose 108, the contribution of the second impedance to the measurement is of no consequence. In other aspects, the second impedance is significantly larger than the first impedance.

[0062] The impedance across the conductive ink first circuit element 104 of hose card 102 (FIGS. 11A-11C) is modified by the amount of conductant material in the ink, the conductive path, the ink thickness, or the stiffness of the members 114 when seated against air hose first end 106. Likewise, the conductivity of second circuit element 110 a/110 b of FIGS. 12A-12C is modified by how far the conductive elements 120 a/120 b are buried in the polymer and the specific conductivity of the polymer material.

[0063] In other aspects of the invention (not shown), the air hose has a shape to encourage a particular alignment. That is, the air hose must be rotated to specific position to insert the air hose into the inlet port. In these circumstances the first circuit element no longer need be annular in shape. Further, since the position of the second circuit element contacts are predetermined, the first circuit element can be shaped to bridge the gap between the second circuit element contacts.

[0064]FIGS. 13A and 13B illustrate an convective warming system using an electronic identification tag 130. The electronic tag 130 provides information. In its simplest form, the tag 130 provides a single bit of information that is used to communicate that an electrical connection has been made. This aspect of the invention is similar in concept to the impedance measurement method described above in the explanation of FIGS. 12A-12C. In other aspects of the invention the electronic tag 130 provides more information, which in turn, permits a wider range of responses.

[0065] Communication with the electronic identification tag 130 can be made through a direct-wired-connection, through a modulated magnetically radiated signal, and a modulated electrically radiated signal. When a direct electrical connection is to be made, any of the above-described methods to interface the first 104 and second 110 circuit elements can be used. However, when radiated signals are to be used, the first 104 and second 110 circuit elements must be radiating elements, or antennas, as shown. Interrogation and identification signals are coupled between radiating elements 104 and 110. When radiated signals are used the electronic identification tags are often called radio frequency identifiers (RF IDs). The higher frequency electric fields can generally be propagated a further distance than the magnetic fields, given the same amount of transmit energy. It may be desirable in some aspects of the invention to limit interrogations from the second circuit element 110, so that the air hose does not communicate with neighboring inflatable thermal devices outfitted with RF IDs.

[0066] The first circuit element 104 at an inlet port of the inflatable device is connected to the electronic identification tag 130 to identify the inflatable device. The second circuit element 110 near the first end 106 of an air hose 108 is receivable in the inlet port 100. The second circuit element 110 cooperates with the first circuit element 104 to enable an identification signal. As mentioned above, the identification signal may just represent a connection between the air hose first end 106 and the inlet port 100. In these circumstances the electronic identification tag provides a 1-bit identification message.

[0067] Alternately, the identification can contain more information bits. At present, electronic identification tags which provide a 64-bit identification code are common, but the present invention is not limited to any particular message length. Among other things, the multiple-bit message can provide information which describes the inflatable thermal device model number, the inflatable thermal device serial number, the preferred air flow rate, the preferred air temperature, and patient identification. The air flow, temperature, and other parameters can be regulated in response to knowing this information. For example, the preferred air flow characteristics may differ for different inflatable thermal device models. Alternately, the tag 130 can be loaded to provide the patients identity, the number of times the blanket has been connected to the warming unit, and the amount of time the blanket has been in use. The air flow controlling mechanism can regulate air flow in response to local database of patient characteristics, or the air flow can be established in communication between the air flow controller and a central system. In other aspects of the invention, the electronic tag is worn by the patient. In some aspects of the invention the electronic tag supplies updated patient vital statistics which are downloaded through the air flow controller to a local file, or communicated to the central system.

[0068] The electronic tag must be powered to transmit a signal. The power can be maintained at the inflatable thermal device. That is, the first circuit element 104 includes a power supply (not shown) directly connected to the electronic identification tag 130. Alternately, the second circuit is directly connected to the power source. Through coupling between radiating elements 104 and 110, the second circuit element 110 cooperates with the first circuit element 104 to power the electronic identification tag 130.

[0069]FIGS. 14A, 14B, 15A-15C, 16A, and 16B illustrate some example of mechanical solutions to the problem of controlling air flow to an inflatable thermal device. These solutions rely on the act of coupling the air hose into the inlet port to open a valve and permit the flow of air. Likewise, the decoupling of the air hose from the inlet port causes the valve to close, preventing bum accidents or improper operation of the equipment. These solution do not rely upon the engagement of electrical contacts, the relaying of electrical signals, or electronic identification for the system to convectively control the temperature of an inflatable thermal device.

[0070]FIG. 14A depicts an inflatable device inlet port 100. The first end 106 of the mating air hose 108 includes a valve 130. As seen in FIG. 14B, as first end 106 of air hose 108 is received in the inlet port 100, the valve 130 cooperating with the inlet port to enable airflow between the hose first end 106 and the inlet port 100. Also, while FIG. 14B depicts the valve flap 136 opening toward the inlet port 100 upon activation, it is also possible to design a valve system in which the flap 136 opens towards the hose 108 upon activation. It should also be noted that the valve is engaged independent of the rotational alignment 132 of the air hose 108 in the inlet port 100. That is, there is no single, or keyed position in which the valve operates.

[0071] The valve 130 includes two primary components, a flap 134 which has a diameter 136 substantially the same as the inner diameter of the air hose first end 106, or at least the air hose diameter that interfaces with the flap. It should be noted that the flap 134 need not perfectly seal the air hose 108 to be effective. The flap 134 blocks the flow of air, or substantially blocks the flow of air, when the air hose 108 is not received in the inlet port 100. The other main component of the valve 130 is the actuating mechanism, of which three examples are shown.

[0072] As depicted in FIGS. 14A and 14B, in one aspect of the invention the valve 130 includes a hinge lever 138 which is rigidly attached to the flap. At the intersection of the hinge lever 138 and flap 134 is an axle or pin (not shown) about which the flap 134 and hinge level 138 pivot. The hinge lever 138 cooperates with the inlet port 100, moving from a position perpendicular to the air hose 108, to a position against the air hose 108, to permit the hose first end 106 to fit inside the inlet port 100. The engagement of the hinge lever 138 prevents the flap 134 from blocking the flow of air when the air hose first end 106 is received in the inlet port 100. Not specifically shown is the mechanism which returns the flap 134 to the blocking position (FIG. 14A) when the air hose 108 is not engaged in the inlet port 100. The return-mechanism can be a spring or some such torsioning member (not shown) which is put under load by the action of the flap being forced into the open position (FIG. 14B). Additionally, in some orientations, the valve flap can be returned to its seated position by the frictional force of the airflow within the air hose 108. Once the valve flap 136 is seated, it will be held in place by the static pressure developed by the blower.

[0073] In some aspects of the invention a pair of magnets 139 a and 139 b are used to keep the flap 134 in the blocking position when the air hose 108 is not received in the inlet port 100. The air hose 108 includes the first magnet 139 a, and the valve flap 134 includes the second magnet 139 b. The first magnet 139 a cooperates with the second magnet 139 b so that the flap 134 blocks the flow of air when the air hose 108 is not received in the inlet port 100. Although not specifically shown, magnets can also be used with the flap 134 of the actuator mechanisms shown in FIG. 15A, described below. In another aspect of the invention, not shown, the flap 134 is opened in the direction of the air hose 108 instead of the inlet port 100, so that the flow of air through hose 108 acts to close the flap 134 when it is not engaged.

[0074]FIGS. 15A through 15C depict the valve flap 134 of FIG. 14A, with a cam actuation mechanism. As shown in FIG. 15A, the flap 134 includes a pair of cams 140 a and 140 b rigidly attached to the flap 134, 180 degrees apart. Alternately, the cam can be attached to an axle running through the diameter of the flap 134, with the axle being rigidly attached to the flap, so that the face of the flap and the cam facets remain in a fixed relationship. The cam includes rounded surfaces which permit the cams 140 a/140 b, and attached flap 134, to rotate as the cam engages the surface surrounding the inlet port 100. The rotation of the cams 140 a/140 b is shown if FIG. 15B. As shown in FIG. 15C, the flat facet surfaces of the cams 140 a/140 b permit those surfaces to fixedly seat against the inlet port as the air hose 108 is engaged. With the cams 140 a/140 b seated, the flap 134 is locked in an open position to permit the flow of air. Not shown is the return mechanism which forces the flap 134 into the blocking position (FIG. 15A). As above, the return mechanism can be a spring, or the like that is put under load as the flap is forced into the open (non-blocking) position.

[0075]FIGS. 16A and 16B depict the gear rack valve actuator mechanism. The mechanism includes a lever 150 which engages the inlet port to open the flap 134. Lever 150 is connected to a first gear 152, the teeth of which are intermeshed with the teeth of a second gear 154. In turn, the second gear 154 is attached to flap 134. As the lever is engaged, it is forced into the body of the hose 108. The action of the lever 150 and the gears 152/154 open the flap 134 so that air can pass through the hose 108 into inlet port 100. In some aspects of the invention a pair of magnets 139 a/139 b are used to keep the flap 134 in the blocking position when the air hose 108 is not received in the inlet port 100. In other aspects, the opening of the flap 134 into the direction of the airflow acts to force the flap 134 into a blocking position when level 150 is not engaged in inlet port 100.

[0076] In some aspects of the invention, the mechanical flap concepts are combined with the any of the methods of interfacing the first circuit element with a second circuit element described in FIGS. 11A-11C, FIGS. 12A-12C, and FIGS. 13A and 13B. These aspects rely on the mechanical valve to permit the flow of air. Information in the electrical signals, whether a simple electrical continuity, resistance measurement, or digital information permit the rate of air flow and air temperature to be regulated.

[0077]FIG. 17 illustrates a method for indicating a condition in a system including an inflatable thermal device, corresponding to FIGS. 11A-11C, and FIGS. 12A-12C. Although depicted as a sequence of steps for clarity, no order should be inferred from the numbering unless explicitly stated. In Step 200 at least one annular inlet port, at least one surface adapted to expel air, and an air hose are included with the pressurized thermal device. The air hose has two ends for delivering a flow of pressurized air to the inflatable thermal device when one end is coupled to the inlet port. Step 202 inserts an end of the air hose into the inlet port of the pressurized thermal device. In Step 204 the pressurized thermal device is operated by conducting a flow of pressurized air through the air hose. Step 206 senses at the inlet port a condition between the inlet port and the end of the air hose, independent of the rotational alignment of the air hose in the inlet port. Step 208 is a product where the conduction of air flow is responsive to the sensed condition.

[0078] The sensing of a condition in Step 206 includes the inlet port forming an electrical connection between the inlet port and the end of the hose. The response to the sensed conditions in Step 208 includes delivering pressurized air in accordance with a first set of parameters when an electrical connection is made between the inlet port and the air hose end, and delivering air in accordance with a second set of parameters when no electrical connection is made between the inlet port and the air hose end. Some parameters which can be varied are flow rate and air temperature.

[0079] In some aspects of the invention Step 200 includes an inlet port that is formed in a hose card having a plurality of deformable members. Then, the insertion of the air hose into the inlet port in Step 202 includes the hose card members gradually stiffening to capture the air hose as the air hose is inserted into the inlet port. Typically, Step 200 includes a hose card where the gradually stiffening members have a surface coated with a conductive ink. Then, the sensing of a condition at the inlet port in Step 206 includes forming an electrical connection across the hose card ink surface. As noted above, the conductive ink is made from conductive elements selected from the group of graphite, copper, silver, and carbon, such the conductive ink is manufactured by Acheson, part number SS 24600, which contains graphite.

[0080] In some aspects of the invention Step 200 includes an air hose end with an electrical contact formed in an annular groove around the outside surface of the hose end which interfaces with the inlet port. Then, the insertion of the air hose into the inlet port in Step 202 includes capturing the deformed hose card members in the annular groove, and the sensing of the condition at the inlet port in Step 206 includes forming an electrical connection between the electrical contact in the annular groove of the air hose end and the hose card conductive ink.

[0081] Alternately, Step 200 includes a second circuit element electrical contact (on the hose end) formed from a highly conductive element underlying the surface of the air hose first end made from a high resistivity polymer. Then, the sensing of the condition at the inlet port in Step 206 includes forming an electrical connection between the highly resistive polymer surface overlying the highly conductive element and the first circuit element.

[0082] Regardless of how the first and second circuit elements are formed, Step 200 includes a first circuit element having a first resistance and the second circuit element having a second resistance. Then, the sensing of the condition at the inlet port in Step 206 includes measuring the impedance of the electrical connection formed by the first and second circuit elements. In some aspects of the invention the response to the measuring of the impedance formed by the connection of the first and second circuit elements in Step 206 includes Step 208 delivering air in accordance with a set of parameters which is responsive to the measured impedance. That is, different airflows and air temperatures can be delivered for different impedances.

[0083]FIG. 18 is a flowchart illustrating a method for indicating a condition in a system including an inflatable thermal device, corresponding to FIGS. 13A and 13B. Step 300 includes at least one inlet port having an electronic identification tag, at least one surface adapted to expel air, and an air hose with the inflatable thermal device. The hose has two ends for delivering a flow of pressurized air to the inflatable thermal device when one end is coupled to the hose card. Step 302 inserts an end of the air hose into the inlet port of the inflatable thermal device. Step 304 communicates with the electronic identification tag. Step 306 identifies the inflatable device at the inlet port. Step 308 is a product where the operation of the inflatable thermal device, by conducting a flow of pressurized air through the air hose, is responsive to identifying the inflatable thermal device.

[0084] In some aspects of the invention Step 300 includes the inlet port having an electrical contact and the air hose end has an electrical contact. Then, the communication with the electronic identification tag in Step 304 includes completing a direct electrical contact between the inlet port contact and the air hose end contact. Alternately, Step 300 includes the inlet port having a radiating element and the air hose end having a radiating element. Then, the communication with the electronic identification tag in Step 304 includes coupling signals between the inlet port radiating element and the air hose end radiating element.

[0085] Step 300 can include the electronic identification tag having a 1-bit identification code, so that the communication with the electronic identification tag in Step 304 includes communicating the 1-bit identification code. Alternately, the tag provides a plurality of bits in the code, such as 64 bits, so that the communication with the electronic identification tag in Step 304 includes communicating the 64-bit identification code. Multi-bit codes permit the communication of information in Step 304 such as the inflatable thermal device model number, the inflatable device serial number, the number of times the inflatable thermal device has been attached, the amount of time the inflatable thermal device has been used, the preferred air flow rate, the preferred air temperature, and the identification of the patient. Thus, it is possible to deliver pressurized air (Step 308) in accordance with a plurality of selectable parameters, where the parameters define such variables as temperature and pressure or flow rate. The parameters selected are responsive to the identification made in Step 306.

[0086] In some aspects of the invention Step 300 includes an inflatable device with a power supply connected to the electronic identification tag. Then, the communication with the electronic identification tag in Step 304 includes powering the electronic identification tag with the power supply. Alternately, Step 300 includes the power supply being permanently connected to conductive elements in the air hose. Then, the communication with the electronic identification tag in Step 304 includes connecting the air hose to the inlet port to provide power to the electronic identification tag.

[0087]FIGS. 11A through 13A, and FIGS. 17-18 describe sensors and sensing methods that vary from the measurement of a simple on/off electrical connection, through the measurement of resistance, to sophisticated identification schemes. These sensing mechanisms and methods permit airflow to be terminated if a disconnection is sensed, or airflow to be regulated after the mating inflatable thermal device is identified. However, inflatable thermal devices must also be used in emergency situations, or to prewarm bedding or clothing prior to use, with whatever equipment is available at the time. In these situations it may be desirable to have the blower unit deliver a predetermined lower temperature or lower pressure airflow, even if a disconnect is sensed, or if the inflatable thermal device cannot be identified, as an alternative to shutting off. It may also be desirable to set an alarm which communicates an improper connection or unidentified inflatable thermal device, and then permit the operator to perform a manual override.

[0088]FIG. 19 is a flowchart illustrating a method for controlling air flow in a system including an inflatable thermal device, corresponding to FIGS. 14A-14B, 15A-15C, and 16A-16B. Step 400 includes the inflatable thermal device having at least one inlet port, at least one surface adapted to expel air, and an air hose having two ends and a valve to prevent the delivery of a flow of pressurized air to the inflatable thermal device. Step 402 inserts an end of the air hose into the inlet port of the inflatable thermal device. Step 404, in response to inserting the air hose into the inlet port, opens the valve. The opening of the valve in Step 404 includes the valve cooperating with the inlet port. Step 406 is a product where the inflatable thermal device is operated by conducting a flow of pressurized air through the air hose.

[0089] Step 400 includes a valve having a flap with a diameter that is substantially the same as the air hose first end diameter. The method further comprises Step 408. Step 408 blocks the flow of air with the valve flap when the air hose is not received in the inlet port.

[0090] In some aspects of the invention Step 400 includes a valve with a hinge lever. Then, the opening of the valve in Step 404 includes the hinge lever cooperating with the inlet port to prevent the flap from blocking the flow of air when the air hose is received in the inlet port.

[0091] In some aspects of the invention Step 400 includes a valve with seating cams. Then, the opening of the valve in Step 404 includes the seating cams cooperating with the inlet port acting to prevent the flap from blocking the flow of air when the air hose is received in the inlet port.

[0092] In other aspects, Step 400 includes an air hose with a first magnet and a valve flap includes a second magnet. Then, the blocking of the air flow in Step 408 includes the first magnet cooperating with the second magnet, positioning the flap to prevent the flow of air when the air hose is not received in the inlet port.

[0093] In some aspects of the invention Step 402 includes making an electrical connection when the air hose end is inserted into the inlet port. As described in detail above, the electrical connection can be an on/off determination, an impedance measurement, or inflatable thermal device identification. Then, Step 406 includes operating the inflatable device by delivering the pressurized air in accordance with parameters that are responsive to the electrical connection made. For example, the inflatable device could be supplied with no air, or less heat, if an electrical connection is not made, regardless of whether the flap is open. Otherwise, the parameters of the airflow such as rate and temperature can be varied in responsive to an impedance measurement, or digital identification of the inflatable thermal device.

[0094] Clearly, other embodiments and modifications of the present invention will occur readily to those of ordinary skill in the art in view of these teachings. For example, in inflatable thermal devices with more than one inlet port, one, some, or all of the inlet ports may have first circuit elements as illustrated in the figures. Also, a heater/blower unit with more than one air hose may fall within the scope of this invention. Further, the invention may be applied to convective systems having the elements of FIG. 1 that cool persons, animals, or things. Therefore, this invention is to be limited only by the following claims, which include all such embodiments and modifications. 

We claim:
 1. In a system for convectively controlling a temperature with an inflatable thermal device, a combination for monitoring a condition between an air hose and an inlet port in the inflatable thermal device, comprising: an inlet port of an inflatable device including an annular first circuit element; and a second circuit element near a first end of an air hose receivable in the inlet port, the second circuit element cooperating with the first circuit element to enable a signal representing a connection between the first end of the air hose and the inlet port, independent of the rotational alignment of the air hose in the inlet port.
 2. The combination of claim 1 in which the second circuit element includes an electrical contact; in which the first circuit element includes an electrical contact forming a conductive link with second circuit element electrical contact.
 3. The combination of claim 2 in which the first circuit element includes a hose card with a plurality of deformable members, gradually stiffening to capture an air hose inserted into the inlet port.
 4. The combination of claim 3 in which the first circuit element deformable members have a surface coated with a conductive ink.
 5. The combination of claim 4 in which the conductive ink includes conductive elements selected from the group of graphite, copper, silver, and carbon.
 6. The combination of claim 4 in which the conductive ink is manufactured by Acheson, part number SS
 24600. 7. The combination of claim 4 in which the second circuit element electrical contact is formed in an annular groove around the outside surface of the first air hose end to capture the first circuit element gradually stiffening members.
 8. The combination of claim 2 in which first end of the air hose is a highly resistive polymer and the second circuit element electrical contact is formed from a highly conductive element underlying the surface of the polymer air hose first end, the first and second circuit elements cooperating to enable a signal between the first circuit element and the polymer hose surface immediately overlying the highly conductive element.
 9. The combination of claim 2 in which the first circuit element has a first impedance, in which the second circuit element has a second impedance, the first and second circuit elements cooperating to provide an impedance which represents a connection between the first end of the hose and the inlet port.
 10. In a system for convectively controlling a temperature with an inflatable thermal device, a combination for controlling airflow between an air hose and an inlet port in the inflatable thermal device, comprising: an inlet port of an inflatable device; and a valve near a first end of an air hose receivable in the inlet port, the valve cooperating with the inlet port to enable airflow between the first end of the air hose and the inlet port.
 11. The combination of claim 10 in which the valve cooperates with the inlet port independent of the rotational alignment of the air hose in the inlet port.
 12. The combination of claim 10 in which the valve includes a flap having a diameter substantially the same as the air hose diameter to block the flow of air when the air hose is not received in the inlet port.
 13. The combination of claim 12 in which the valve includes a hinge lever, the hinge lever cooperating with the inlet port to prevent the flap from blocking the flow of air when the air hose is received in the inlet port.
 14. The combination of claim 12 valve includes seating cams, the seating cams cooperating with the inlet port to prevent the flap from blocking the flow of air when the air hose is received in the inlet port.
 15. The combination of claim 12 in which the air hose includes a first magnet, in which the valve flap includes a second magnet, the first magnet cooperating with the second magnet so that the flap blocks the flow of air when the air hose is not received in the inlet port.
 16. The combination of claim 12 in which the air hose includes a gear rack mounted lever cooperating with the inlet port to prevent the flap from blocking the flow of air when the air hose is received in the inlet port.
 17. In a system for convectively controlling a temperature with an inflatable thermal device, a combination for monitoring a condition between an air hose and an inlet port in the inflatable thermal device, comprising: a first circuit element at an inlet port of an inflatable device connected to an electronic identification tag to identify the inflatable device; and a second circuit element near a first end of an air hose receivable in the inlet port, the second circuit element cooperating with the first circuit element to enable an identification signal representing a connection between the first end of the air hose and the inlet port.
 18. The combination of claim 17 in which the first circuit element includes an electrical contact; and in which the second circuit element includes an electrical contact, cooperating with the electrical contact of first circuit element by forming a direct connection to enable the identification signal.
 19. The combination of claim 17 in which the first circuit element includes a radiating element; in which the second circuit includes a radiating element, the second circuit cooperating with the first circuit element by coupling signals between the second circuit element radiator and the first circuit element radiator.
 20. The combination of claim 17 in which the electronic identification tag provides a 1-bit identification code.
 21. The combination of claim 17 in which the electronic identification tag provides a 64-bit identification code.
 22. The combination of claim 21 in which the 64-bit identification provides information including the inflatable thermal device model number, the inflatable thermal device serial number, the preferred air flow rate, the preferred air temperature, and patient identification.
 23. The combination of claim 17 in which the first circuit element includes a power supply connected to the electronic identification tag.
 24. The combination of claim 17 in which second circuit element is connected to a power supply, and in which the second circuit element cooperates with the first circuit element to power the electronic identification tag with the power supply.
 25. An inflatable thermal device system, comprising: an inflatable thermal device with at least one inlet port and at least one surface adapted to expel air; an air hose with a first end and a second end; an inlet port of an inflatable device including an annular first circuit element; a second circuit element near a first end of an air hose receivable in the inlet port, the second circuit element cooperating with the first circuit element to enable a signal representing a connection between the first end of the air hose and the inlet port independent of the alignment of the air hose in the inlet port; and one or more conductors in the air hose connected to the second circuit element for conducting the signal from the first to the second end.
 26. The device of claim 25 in which the second circuit element includes an electrical contact; in which the first circuit element includes an electrical contact, forming a conductive link with the second circuit element electrical contact.
 27. The device of claim 26 in which the first circuit element includes a hose card with a plurality of deformable members, gradually stiffening to capture an air hose inserted into the inlet port.
 28. The device of claim 27 the first circuit element deformable members have a surface coated with a conductive ink.
 29. The device of claim 28 in which the conductive ink includes conductive elements selected from the group of graphite, copper, silver, and carbon.
 30. The device of claim 28 in which the conductive ink is manufactured by Acheson, part number SS
 24600. 31. The device of claim 28 in which the second circuit element electrical contact is formed in an annular groove around the outside surface of the first air hose end to capture the first circuit element gradually stiffening members.
 32. The device of claim 26 in which first end of the air hose is highly resistive polymer and the second circuit element electrical contact is formed from a highly conductive element underlying the surface of the polymer air hose first end, the first and second circuit elements cooperating to enable a signal between the first circuit element and the polymer hose surface immediately overlying the highly conductive element.
 33. The device of claim 26 in which the first circuit element has a first impedance, in which the second circuit element has a second impedance, the first and second circuit elements cooperating to provide an impedance which represents a connection between the first end of the hose and the inlet port.
 34. An inflatable thermal device system, comprising: an inflatable thermal device with at least one inlet port and at least one surface adapted to expel air; an air hose with a first end and a second end; a valve near the first end of an air hose receivable in the inlet port, the valve cooperating with the inlet port to enable airflow between the first end of the air hose and the inlet port.
 35. The device of claim 34 in which the valve cooperates with the inlet port independent of the rotational alignment of the air hose first end in the inlet port.
 36. The device of claim 34 in which the air hose has a first diameter; and in which the valve includes a flap with the first diameter to block the flow of air when the air hose first end is not received in the inlet port.
 37. The device of claim 36 in which the valve includes a hinge lever, the hinge lever cooperating with the inlet port to prevent the flap from blocking the flow of air when the air hose first end is received in the inlet port.
 38. The device of claim 36 valve includes seating cams, the seating cams cooperating with the inlet port to prevent the flap from blocking the flow of air when the air hose first end is received in the inlet port.
 39. The device of claim 36 in which the air hose includes a first magnet, in which the valve flap includes a second magnet, the first magnet cooperating with the second magnet so that the flap blocks the flow of air when the air hose is not received in the inlet port.
 40. The device of claim 36 in which the air hose includes a gear rack mounted lever cooperating with the inlet port to prevent the flap from blocking the flow of air when the air hose is received in the inlet port.
 41. An inflatable thermal device system, comprising: an inflatable thermal device with at least one inlet port and at least one surface adapted to expel air; an air hose with a first end and a second end; a first circuit element at an inlet port of an inflatable device connected to an electronic identification tag to identify the inflatable device; and a second circuit element near a first end of an air hose receivable in the inlet port, the second circuit element cooperating with the first circuit element to enable an identification signal representing a connection between the first end of the air hose and the inlet port; and one or more conductors in the air hose connected to the second circuit element for conducting the signal from the first to the second end.
 42. The device of claim 41 in which the first circuit element includes an electrical contact; and in which the second circuit element includes an electrical contact, the second circuit cooperating with the first circuit element by making direct connection between the electrical contacts of the first circuit element and the second circuit element.
 43. The device of claim 41 in which the first circuit element includes a radiating element; in which the second circuit includes a radiating element, the second circuit cooperating with the first circuit element by coupling signals between the second circuit element radiator and the first circuit element radiator.
 44. The device of claim 41 in which the electronic identification tag provides a 1-bit identification code.
 45. The device of claim 41 in which the electronic identification tag provides a 64-bit identification code.
 46. The device of claim 45 in which the 64-bit identification provides information including the inflatable thermal device model number, the inflatable thermal device serial number, the preferred air flow rate, the preferred air temperature, and patient identification.
 47. The device of claim 41 in which the first circuit element includes a power supply connected to the electronic identification tag.
 48. The device of claim 41 in which second circuit element is connected to a power supply, and in which the second circuit element cooperates with the first circuit element to power the electronic identification tag with the power supply.
 49. A method for indicating a condition in a system including an inflatable thermal device with at least one annular inlet port, at least one surface adapted to expel air, and an air hose with two ends for delivering a flow of pressurized air to the inflatable thermal device when one end is coupled to the inlet port, comprising: inserting an end of the air hose into the inlet port of the inflatable thermal device; operating the inflatable thermal device by conducting a flow of pressurized air through the air hose; independent of the rotational alignment of the air hose in the inlet port, sensing at the inlet port a condition between the inlet port and the end of the air hose; and responding to the sensed condition.
 50. The method of claim 49 in which the sensing of a condition at the inlet port includes forming an electrical connection between the inlet port and the end of the hose.
 51. The method of claim 50 wherein the inlet port is formed in a hose card having a plurality of deformable members; and in which the insertion of the air hose into the inlet port includes the hose card members gradually stiffening to capture the air hose as the air hose is inserted into the inlet port.
 52. The method of claim 51 wherein the hose card gradually stiffening members have a surface coated with a conductive ink; and in which the sensing of a condition at the inlet port includes forming an electrical connection across the hose card ink surface.
 53. The method of claim 52 wherein the conductive ink includes conductive elements selected from the group of graphite, copper, silver, and carbon.
 54. The method of claim 52 in which the conductive ink is manufactured by Acheson, part number SS
 24600. 55. The method of claim 52 wherein the air hose end includes an electrical contact formed in an annular groove around the outside surface; in which the insertion of the air hose into the inlet port includes capturing the deformed hose card members in the annular groove; and in which the sensing of the condition at the inlet port includes forming an electrical connection between the electrical contact in the annular groove of the air hose end and the hose card conductive ink.
 56. The method of claim 50 wherein the second circuit element electrical contact is formed from a highly conductive element underlying the surface of the air hose first end made from a high resistivity polymer; and in which the sensing of the condition at the inlet port includes forming an electrical connection between the highly resistive polymer surface overlying the highly conductive element and the first circuit element.
 57. The method of claim 50 wherein the first circuit element has a first resistance and the second circuit element has a second resistance; and in which the sensing of the condition at the inlet port includes measuring the impedance of the electrical connection formed by the first and second circuit elements.
 58. The method of claim 57 in which the response to the measuring of the impedance formed by the connection of the first and second circuit elements includes delivering air in accordance with a set of parameters which are responsive to the measured impedance.
 59. The method of claim 50 in which the response to the sensed condition includes delivering pressurized air in accordance with a first set of parameters when an electrical connection is made between the inlet port and the air hose end, and delivering air in accordance with a second set of parameters when no electrical connection is made between the inlet port and the air hose end.
 60. A method for controlling air flow in a system including an inflatable thermal device with at least one inlet port, at least one surface adapted to expel air, an air hose having two ends, and a valve to prevent the delivery of a flow of pressurized air to the inflatable thermal device, comprising: inserting an end of the air hose into the inlet port of the inflatable thermal device; in response to inserting the air hose into the inlet port, opening the valve; and operating the inflatable thermal device by conducting a flow of pressurized air through the air hose;
 61. The method of claim 60 in which opening of the valve includes the valve cooperating with the inlet port.
 62. The method of claim 61 wherein the valve includes a flap having a diameter substantially the same as the air hose diameter, the method further comprising: blocking the flow of air with the valve flap when the air hose is not received in the inlet port.
 63. The method of claim 62 wherein the valve includes a hinge lever; and in which the opening of the valve includes the hinge lever cooperating with the inlet port to prevent the flap from blocking the flow of air when the air hose is received in the inlet port.
 64. The method of claim 62 wherein the valve includes seating cams; and in which the opening of the valve includes the seating cams cooperating with the inlet port acting to prevent the flap from blocking the flow of air when the air hose is received in the inlet port.
 65. The method of claim 62 wherein the air hose includes a first magnet and the valve flap includes a second magnet; and in which the blocking of the air flow includes the first magnet cooperating with the second magnet, positioning the flap to prevent the flow of air when the air hose is not received in the inlet port.
 66. The method of claim 62 wherein the air hose includes a gear rack mounted lever; and in which the opening of the valve includes the gear rack mounted lever cooperating with the inlet port acting to prevent the flap from blocking the flow of air when the air hose is received in the inlet port.
 67. The method of claim 62 in which the insertion the insertion of the air hose end into the inlet port of the inflatable thermal device includes making an electrical connection; and in which the operation of the inflatable thermal device includes delivering a pressurized flow of air in accordance with parameters which are selected in response to making the electrical connection.
 68. A method for indicating a condition in a system including an inflatable thermal device with at least one inlet port having an electronic identification tag, at least one surface adapted to expel air, and an air hose with two ends for delivering a flow of pressurized air to the inflatable thermal device when one end is coupled to the inlet port, comprising: inserting an end of the air hose into the inlet port of the inflatable thermal device; communicating with the electronic identification tag; identifying the inflatable device at the inlet port; and in response to identifying the inflatable thermal device, operating the inflatable thermal device by conducting a flow of pressurized air through the air hose.
 69. The method of claim 68 wherein the inlet port includes an electrical contact, and wherein the air hose end includes an electrical contact; and in which communication with the electronic identification tag includes completing a direct connection between the inlet port contact and the air hose end contact.
 70. The method of claim 68 wherein the inlet port includes a radiating element, and wherein the air hose end includes a radiating element; and in which communication with the electronic identification tag includes coupling signals between the inlet port radiating element and the air hose end radiating element.
 71. The method of claim 68 wherein the electronic identification tag provides a 1-bit identification code; and in which communication with the electronic identification tag includes communicating the 1-bit identification code.
 72. The method of claim 68 wherein the electronic identification tag provides a 64-bit identification code; and in which communication with the electronic identification tag includes communicating the 64-bit identification code.
 73. The method of claim 72 in which the communication of the 64-bit identification code includes communicating information including the inflatable thermal device model number, the inflatable device serial number, the preferred air flow rate, the preferred air temperature, and the identification of the patient.
 74. The method of claim 68 wherein the inflatable device includes a power supply connected to the electronic identification tag; and in which communication with the electronic identification tag includes powering the electronic identification tag with the power supply.
 75. The method of claim 68 wherein the air hose includes a connection to a power supply; and in which communication with the electronic identification tag includes connecting the air hose to the inlet port to provide power to the electronic identification tag.
 76. The method of claim 68 in which the operation of the inflatable thermal device includes delivering a flow of pressurized air through the air hose in accordance with a plurality selectable parameters, and in which the operating parameters are selected in response to the identity of the inflatable device. 